Stacked multilayer structure and manufacturing method thereof

ABSTRACT

A stacked multilayer structure according to an embodiment of the present invention comprises: a stacked layer part including a plurality of conducting layers and a plurality of insulating layers, said plurality of insulating layers being stacked alternately with each layer of said plurality of conducting layers, one of said plurality of insulating layers being a topmost layer among said plurality of conducting layers and said plurality of insulating layers; and a plurality of contacts, each contact of said plurality of contacts being formed from said topmost layer and each contact of said plurality of contacts being in contact with a respective conducting layer of said plurality of conducting layers, a side surface of each of said plurality of contacts being insulated from said plurality of conducting layers via an insulating film.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2007-173445, filed on Jun. 29,2007; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a stacked multilayer structure, amanufacturing method thereof, and a semiconductor device using saidstacked multilayer structure.

2. Description of the Related Art

The demand for miniature and large capacity nonvolatile semiconductordevices is increasing. In order to realize this miniaturization andlarge scale capacity, a number of devices in which semiconductorelements such as memory cell transistors are arranged threedimensionally have been proposed. For example, such devices aredisclosed in the United States Patent Publication No. US-20020154556-A1,the U.S. Pat. No. 5,599,724, U.S. Pat. No. 5,707,885, and Masuoka et al,“Novel Ultrahigh-Density Flash Memory With a Stacked-Surrounding GateTransistor (S-SGT) Structured Cell” IEEE TRANSACTIONS ON ELECTRONDEVICES, Vol. 50, N04, pp 945-951, April 2003.

In such devices in which semiconductor elements and the like arearranged three dimensionally, a plurality of conducting layers arestacked to form a stacked multilayer structure, each of said pluralityof conducting layers being connected to several electrodes of saidelements positioned on the same layer. And there is a need to connecteach of said plurality of conducting layers to a driving circuit.Thereupon, there is a need to form efficiently these connectionstructures while keeping their reliability.

BRIEF SUMMARY OF THE INVENTION

A stacked multilayer structure according to an embodiment of the presentinvention comprises: a stacked layer part including a plurality ofconducting layers and a plurality of insulating layers, said pluralityof insulating layers being stacked alternately with each layer of saidplurality of conducting layers, one of said plurality of insulatinglayers being a topmost layer among said plurality of conducting layersand said plurality of insulating layers; and a plurality of contacts,each contact of said plurality of contacts being formed from saidtopmost layer and each contact of said plurality of contacts being incontact with a respective conducting layer of said plurality ofconducting layers, a side surface of each of said plurality of contactsbeing insulated from said plurality of conducting layers via aninsulating film.

A nonvolatile semiconductor device according to an embodiment of thepresent invention comprises: a stacked layer part including a pluralityof conducting layers, a plurality of insulating layers and a pluralityof semiconductor pillars, said plurality of insulating layers beingstacked alternately with each layer of said plurality of conductinglayers, one of said plurality of insulating layers being a topmost layeramong said plurality of conducting layers and said plurality ofinsulating layers, and each of said plurality of semiconductor pillarshaving a nonvolatile memory cell around the section of penetration intoeach of said plurality of conducting layers; a plurality of contacts,each contact of said plurality of contacts being formed from saidtopmost layer and each contact of said plurality of contacts being incontact with a respective conducting layer of said plurality ofconducting layers, a side surface of each of said plurality of contactsbeing insulated from said plurality of conducting layers via aninsulating film; and a driving circuit being connected to each of saidplurality of conducting layers respectively via said plurality ofcontacts.

A manufacturing method according to an embodiment of the presentinvention of a stacked multilayer structure comprises: stacking aconducting layer and a plurality of insulating layer alternately, one ofsaid insulating layer being a topmost layer among a plurality ofinsulating layers and a plurality of conducting layers; forming aplurality of contact holes, each of said plurality of contact holesbeing in contact with a top surface of said conducting layersrespectively from said topmost layer; forming an insulating film on aside surface of said plurality of contact holes; and forming contacts bydepositing conducting material inside said plurality of contact holes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an outline of an external view of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 2 shows a cross sectional diagram of a stacked multilayer structurerelated to one embodiment of the present invention.

FIG. 3 shows an outline of an external view of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 4 shows an outline of an external view of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 5 shows an outline of an external view of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 6 shows an outline of an external view of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 7 shows an outline structure of a nonvolatile semiconductor memorydevice which uses a stacked multilayer structure related to oneembodiment of the present invention.

FIG. 8 shows an outline structure of a nonvolatile semiconductor memorydevice which uses a stacked multilayer structure related to oneembodiment of the present invention.

FIG. 9 is a diagram for explaining the formation of a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 10 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 11 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 12 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 13 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 14 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 15 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 16 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 17 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 18 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 19 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 20 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 21 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 22 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 23 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 24 is a diagram for explaining the formation of a stacked wirestructure body related to one embodiment of the present invention.

FIG. 25 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 26 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 27 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 28 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 29 is a diagram for explaining the formation of a stackedmultilayer structure related to one embodiment of the present invention.

FIG. 30 shows a memory string of a non-volatile semiconductor memorydevice and its equivalent circuit which uses a stacked multilayerstructure related to one embodiment of the present invention.

FIG. 31 shows an outline structure of a nonvolatile semiconductor memorydevice which uses a stacked multilayer structure related to oneembodiment of the present invention.

FIG. 32 shows a cross section of a memory element of a nonvolatilesemiconductor memory device and its equivalent circuit which uses astacked multilayer structure related to one embodiment of the presentinvention.

FIG. 33 shows a cross section of memory strings which are formed from aphase change type memory element of a nonvolatile semiconductor memorydevice which uses a stacked multilayer structure related to oneembodiment of the present invention.

FIG. 34 shows a cross section view of a phase change type memory elementof a nonvolatile semiconductor memory device and its equivalent circuitwhich uses a stacked multilayer structure related to one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

Now, embodiments of a stacked multilayer structure, its manufacturingmethod thereof, and a semiconductor device using said stacked multilayerstructure of the present invention will be described in detail withreference to the drawings. Furthermore, the present invention is notlimited to these embodiments. A variety of embodiments are possible. Inaddition, because identical reference numerals are used to the sameconstituents, some explanations of which will be omitted from thedescription.

First Embodiment

FIG. 1 shows an outline drawing of an external aspect of a semiconductordevice related to one embodiment of the present invention. Thesemiconductor device 100 includes a stacked layer part in whichconducting layers and insulating layers are alternately stacked. Thestacked layer part may be arranged with an element region 101 and acontact region 102. The element region 101 is a region in whichsemiconductor elements exist. These semiconductor elements are formedafter the conducting layers and the insulating layers are alternatelystacked. However, the conducting layers, the insulating layers, and thesemiconductor elements may be formed in any order.

In addition, even in the case where the semiconductor device includes noelement region 101, the semiconductor device can be regarded asincluding a stacked multilayer structure related to one embodiment ofthe present invention. In other words, it is also possible to identifythe contact region 101 as a stacked multilayer structure related to oneembodiment of the present invention.

The contact region 102 is a region in which contacts for electricallyconnecting each conducting layer to a wire, which are not shown in thedrawing and positioned on or above the topmost layer 112. Furthermore,such wire may be connected to, for example, a driving circuit, which isalso not shown in the drawing. Here, the topmost layer 112 need not tobe literally topmost. As explained here, above the topmost layer 112,there may be another layer. The ‘topmost’ of ‘the topmost layer 112’ maymean that the layer is uppermost when forming contacts.

The semiconductor device 100 includes, for example, a substrate layer103 located at the bottom and, above the substrate 103 an insulatinglayer 104, a conducting layer 105, an insulating layer 106, a conductinglayer 107, an insulating layer 108, a conducting layer 109, aninsulating layer 110, a conducting layer 111, and an insulating layer112 are stacked alternately in this order. The insulating layers 104,106, 108, and 110 are formed, for example, as silicon oxide films andthe conducting layers 105, 107, 109, and 111 are formed, for example, aspolysilicon films or as amorphous silicon films in which conductingimpurities such as phosphorus have been doped. In addition, the topmostinsulating layer 112 may be formed by a different material from theother insulating layers 104. 106. 108 and 110, so that it may alsofunction as a protection layer. Of course, there is no need to form theinsulating layers 104, 106, 108 and 110 by depositing the same materialand the thickness of each layer may also be different. In addition,there is no need to form the conducting layers 105, 107, 109 and 111 bydepositing the same material and the thickness of each layer may also bedifferent.

The contacts 113, 114, 115 and 116, which have been formed in thecontact holes, exist in the contact region 102. For example, the contact113 has been formed by a photo etching process for forming a contacthole which reaches the conducting layer 105 and following the formationof the contact hole, an insulating film forming process of the otherconducting layers 107, 109, and 111 is performed so that the contact 113can be connected electrically only to the bottom conducting layer 105.The forming process of the contact 113 is completed by depositingsilicon which has been doped with phosphorus or a metal contact plugsuch as tungsten in the contact hole. Similarly, the contact 114 hasbeen formed so that it is connected electrically with only with theconducting layer 107, the contact 115 is formed so that it is connectedelectrically only with the conducting layer 109, and the contact 116 isformed so that it is connected electrically only with the conductinglayer 111.

FIG. 2 is a cross sectional diagram of the contact region 102. That is,FIG. 2 shows a cross section along with a line passing roughly throughthe centers of the contacts 113, 114, 115, and 116. The substrate layer103 is arranged at the bottom and above this substrate layer 103, theinsulating layer 104, the conducting layer 105, the insulating layer106, the conducting layer 107, the insulating layer 108, the conductinglayer 109, the insulating layer 110, the conducting layer 111, and theinsulating layer 112 are stacked alternately in this order. The fourcontacts 2501 are shown in FIG. 2. So it can be considered, for example,that from the right hand side to the left hand side each of the contacts2501 corresponds to each of the contacts 113, 114, 115, and 116, whichare shown in FIG. 1.

Each conducting layer at the bottom of each of the contacts 2501 isconnected electrically with each contact. Alternatively, the part of theconducting layer at the side surface of each of contacts 2501 isinsulated from each contact by the oxidization process etc. That is,there is an insulating film between the side surface of each of thecontact 2501 and each conducting layer above the bottom conducting layerof each contact. As a result, the conducting layers apart from theconducting layer which is at the bottom of each of the contacts 2501 areinsulated from the contacts 2501. Furthermore, although the sidesurfaces of each of the contacts 2501 are shown to be perpendicular tothe substrate layer 103, as will be described later, they are notlimited to be perpendicular to the substrate layer 103.

There are a number of varying arrangements of the contacts in a stackedmultilayer structure and a semiconductor device related to oneembodiment of the present invention. For example, in FIG. 3, thecontacts 113, 114, 115, and 116 are arranged in a diagonal line at a 45degree angle to the element region 101. Alternatively, in FIG. 1, thecontacts 113, 114, 115, and 116 are arranged in a line at a 90 degreeangle to the element region 101. By arranging the contacts 113, 114,115, and 116 as FIG. 3, it is possible to increase the distance betweencontacts compared with the arrangement shown in FIG. 1. As a result, itis possible to prevent a contact hole from connecting with other contacthole at the time of contact hole formation. In addition, it is alsopossible to reduce the width of the contact region compared with that inFIG. 1.

Also, a contact may be placed at any place in the contact region 102.For example, as shown in FIG. 4, the contacts 113, 114, 115, and 116 maybe arranged on both sides of the line 117, which may be virtually drawnat the center of the contact region 102. In FIG. 4, each of the contacts113, 114, 115, and 116 is placed at each peak of a triangle wave, theamplitude of which is gradually changing. In other words, the contacts113 and 115 are placed on one side of the line 117 and the contacts 114and 116 are placed on the other side of the line 117 in a zig zag shapeso that the closer to the element part 104 the contact hole is, thelarger the distance between the contact and the line 117 becomes. Thecontacts may be also arranged so that the closer to the element part 104the contact hole is the smaller the distance between the contact and theline 117 becomes. Furthermore, each of the contacts may be placed ateach peak of a sawtooth wave instead of a triangle wave. By arrangingthe contacts in one of such ways, it is possible to increase thedistance between contacts compared with that in FIG. 2 or FIG. 3. As aresult, as well as being able to prevent a contact hole from connectingwith other contact hole at the time of contact hole formation, it isalso possible to reduce the width of the contact region compared to thatin FIG. 1 or FIG. 3. Furthermore, the line 117 may be a straight linewhich extends in a perpendicular direction to the contact region 102 tothe border between the element region 101 and the contact region 102,but it needs not to be restricted to this case.

In addition, for example, the contacts 113, 114, 115, and 116 in FIG. 5are arranged in a line substantially parallel to the element region 101.In other words, they are arranged in a line which parallels the borderbetween the element region 101 and the contact region 102, or they arearranged in a line which parallels the outside edge of the contactregion 102. By arranging the contacts in a line which parallels a borderas described here it is possible to reduce the depth (the distancebetween the border of the element region and the contact region and theedge opposite to the border of the contact region) of the contact regioncompared with that in FIG. 3 or FIG. 4.

In addition, for example, in FIG. 6 (A), in addition to the contacts113, 114, 115, and 116, the contacts 118, 119, 120 and 121 are arranged.These contacts are arranged in two lines which parallel the borderbetween the element region 101 and the contact region 102, or they arearranged in two lines which parallel the outside edge of the contactregion 102. Furthermore these contacts may be arranged in a grid shape.By arranging the contacts in two lines or more which parallel a borderas describe here it is possible to arrange the contacts in a narrower orsmaller contact region even in the case where there are eight conductinglayers as shown in FIG. 6 (A). For example, the contact 113 is incontact with the bottom conducting layer. Then, the contacts 114, 115,116, 118, 119, 120, and 121 can be connected to corresponding conductinglayers in this order from the substrate to the topmost layer.

FIG. 6 (B) is a diagram showing a top view of the semiconductor device100 shown in FIG. 6 (A). As is shown in FIG. 6 (B), the line of contacts113, 114, 115, 116 and the line of the contacts 118, 119, 120, 121, andthe line of the contacts 113 and 118, the line of the contacts 114 and119, the line of the contacts 115 and 120 and the line of the contacts116 and 121 form square shapes or rectangle shapes. In other words, theedges connecting the contacts 118, 113, 119, 114, 120, 115, 121, and 116form a sawtooth wave.

In addition, as is shown in FIG. 6 (C), the row of contacts 113, 114,115, 116 and the row of contacts 118, 119, 120, 121 which are arrangedin a line which parallels the border between the element region 101 andthe contact region 102, may be slightly misaligned by about half thedistance between two contacts in the same row. In addition, the shapemay also be a trapezium. In other words, the shape which has beenexplained above may be a rhomboid or a parallelogram. In other words,the edges connecting the contacts 118, 113, 119, 114, 120, 115, 121, and116 form a triangle wave. By arranging the contacts in a line in thisway it is possible to arrange them in a smaller region.

Furthermore, FIG. 1, FIG. 3, FIG. 4, FIG. 5 and FIG. 6 show a roughexternal view of a semiconductor device or a stacked multilayerstructure related to one embodiment of the present invention as anexample and there is no need for a semiconductor device and a stackedmultilayer structure related to one embodiment of the present inventionto have rectangular parallelepiped shapes. A semiconductor device and astacked multilayer structure related to one embodiment of the presentinvention may have arbitrary three dimensional shapes. In addition, inthe case where there is an element region 101, there is no need for theborder between the element region and contact region to be a straightline when a semiconductor device or a stacked multilayer structurerelated to one embodiment of the present invention is viewed from aboveand a semiconductor device and a stacked multilayer structure related toone embodiment of the present invention may have an arbitrary twodimensional shape. In addition, the element region may be formed by aplurality of regions. This is also the same for the contact region.Furthermore, the number of conducting layers is not limited to four andcan be eight, sixteen, or an arbitrary number.

Second Embodiment

FIG. 7 shows a rough structural view of a nonvolatile semiconductordevice which uses a stacked multilayer structure related to the secondembodiment of the present invention. The nonvolatile semiconductordevice 400 includes a structure in which a first insulating film, anelectron accumulation film, a second insulating film, and a gateelectrode are formed in this order around each of semiconductor pillarsso that each semiconductor pillar can form a memory string connectingmemory transistors in series, said semiconductor pillars being arrangedin a matrix shape. The nonvolatile semiconductor device 400 has fourstacked conducting layers, each layer connecting the gate electrodes ofthe memory transistors at a same level of the semiconductor pillars.Although it has been omitted in the diagram in FIG. 7, there is aninsulating layer above and below these conducting layers. A region wherememory transistors are stacked around semiconductor pillars, which aresubstantially perpendicular to the bottom substrate, corresponds to theelement region 101 shown in FIG. 1, FIG. 3, FIG. 4, FIG. 5, or FIG. 6.Although the nonvolatile semiconductor device 400 shown in FIG. 7, theCommon WL1, the Common WL2, the Common WL3, and the Common WL4, whichare plate shaped and form the conducting layers in the region B, haveparts drawn in dotted lines, these dotted lines are for descriptivepurposes. That is, these dotted lines are for explaining the structureof the contacts connected to the plate shaped Common WL1, the CommonWL2, the Common WL3, and the Common WL4 in the present embodiment.Actually, the Common WL2, the Common WL3 and the Common WL4 extend tothe right of region B similarly as Common WL1 extends. In other words,the Common WL1, the Common WL2, the Common WL3, and the Common WL4correspond to the conducting layers 105, 107, 109 and 111 in FIG. 1,FIG. 3, FIG. 4, FIG. 5 or FIG. 6. In addition, the insulating layer ofthe layer under the Common WL1, each insulating layer among the CommonWL1, the Common WL2, Common WL3, and Common WL4 and the insulating layeron the Common WL4 correspond to the insulating layers 104, 106, 108, 110and 112.

In the nonvolatile semiconductor device 400, which is shown in FIG. 7,four contact holes have been formed so that the four contact holesrespectively can reach the Common WL1, the Common WL2, the Common WL3,and Common WL4 respectively, four contacts which contact with the CommonWL1, the Common WL2, the Common WL3, and the Common WL4 have beenformed, and a word line driving circuit which is not illustrated in thedrawing is connected to each of the Common WL1, the Common WL2, theCommon WL3, and the Common WL4.

FIG. 8 shows a rough structural view of another nonvolatilesemiconductor device which uses a stacked multilayer structure relatedto one embodiment of the present invention. The nonvolatilesemiconductor device 500 includes a memory transistor region 2, a wordline driving circuit 3, a source side selection gate line drivingcircuit 4, a drain side selection gate line driving circuit 5, a bitline (BL) 8, a source side selection gate line 30 and a drain sideselection gate line 31. Similarly to the nonvolatile semiconductordevice shown in FIG. 7, the memory transistor region 2 includes astructure in which a first insulating film, an electron accumulationfilm, a second insulating film, and a gate electrode are formed in thisorder around each of semiconductor pillars so that each semiconductorpillar can form a memory string connecting memory transistors in series,said semiconductor pillars being arranged in a matrix shape. The memorytransistor region 2 corresponds to the element region 101 of the stackedmultilayer structure 100. Also, the word lines WL7 of the nonvolatilesemiconductor device 500 are formed substantially parallel each other inthe memory transistor region 2 and each contact connects electricallyeach word line to each second word line lead line 7 b. Here, the wordlines WL7 have the parts drawn in dotted lines. These dotted lines arefor descriptive purposes as in FIG. 7. Each word line which is shown asword line WL7 corresponds to the conducting layers 105, 107, 109, and111 shown in FIG. 1, FIG. 3, FIG. 5, and FIG. 6. The layer immediatelybelow the bottom word line WL7, each layer between the word lines WL7and the layer immediately above the topmost word line WL7 corresponds tothe insulating layers 104, 106, 108, 110, and 112.

Third Embodiment

A manufacturing process of a stacked multilayer structure related to thethird embodiment of the present invention is explained below withreference to FIG. 9 to FIG. 16. A stacked multilayer structure relatedto the third embodiment of the present invention can be applied to thesemiconductor devices such as those explained in the second embodimentof the present invention.

As is shown in FIG. 9, for example, a stacked multilayer structure of anembodiment of the present invention includes an insulating layer 104, aconducting layer 105, an insulating layer 106, a conducting layer 107,an insulating layer 108, a conducting layer 109, an insulating layer110, a conducting layer 111, and an insulating layer 112 stacked above asubstrate layer 103 alternately in this order. Furthermore, there is noneed for the entire substrate layer 103 to have a uniform structure. Avariety of semiconductor elements can be formed in a certain part of thesubstrate layer to form an element region above said region. Forexample, there may be a region in the substrate layer 103 in which SGSor the source side selection gate 30 are formed as shown in FIG. 7 andFIG. 8. In addition, another insulating layer having a differentmaterial from the insulating layer 112 can be formed above theinsulating layer 112. This insulating layer may function as a protectionlayer.

Similarly, there is no need for all the insulating layers and theconducting layers which are stacked above the substrate layer 103 tohave a uniform structure. For example, it is possible to arrange anelement region (not shown in the drawing) such as that shown in FIG. 7and FIG. 8 being positioned on the left side or the right side of thestacked multilayer structure shown in FIG. 9. Alternatively, the elementregion may be positioned before or after the stacked multilayerstructure shown in FIG. 9.

A photoresist 113 is deposited above the insulating layer 112, which isthe topmost layer, in order to form a contact hole as explained below. Apositive type and a negative type resist are known as two photoresisttypes. Usually, it is possible to increase the resolution by using apositive resist whereas a negative resist has good adhesive properties.Because a contact hole which is formed in an embodiment of the presentinvention has often a large aspect ratio to reach a semiconductor layerwhich is not adjacent to the topmost layer, the negative resist ispreferably used.

In order to form the contact hole which reaches the bottom conductinglayer 105, a photolithography process is performed. Namely, aphotoresist is formed as a contact hole pattern and an etching process,for example RIE (Reactive Ion Etching) is performed using a mask formedby this photo resist. In this way, the contact hole 2001, which reachesthe conducting layer 105 is formed as shown in FIG. 10. Here, anover-etching process may be performed so that the conducting layer andthe contact formed in the contact hole can be surely electricallyconnected. As a result, the bottom surface of this contact hole may beformed not only reaching on the surface of the conducting layer but mayalso be formed into the conducting layer. Following this, thephotoresist 113 is removed.

Next, in order to form another contact hole, another photolithographyprocess is performed. To prevent the contact hole 2001 being etchedfurther the entire upper surface on which the contact hole 2001 appearsis deposited by the photoresist 114. Following this, the photo resist is114 is patterned, a pattern of the contact holes which are connected tothe conducting layer 107 is formed and the etching process is performedusing a mask formed on the photoresist 114. In this way, as shown inFIG. 11, the contact hole 2101 which reaches the conducting layer 107 isformed. Following this, this photoresist is removed.

A process such as that explained above is repeated and as shown in FIG.12, and the contact holes 2201 and 2202 which reach the conductinglayers 109 and 111 respectively, are formed.

Furthermore, according to the above explanation, the order of formingthe contact holes begins by forming the contact hole which reach thebottom conducting layer 105. However, the order of forming the contactholes may be arbitrary. However, as explained above, by forming deepercontact holes earlier, deeper contact holes are filled with photoresistwhen shallower contact holes are being formed, and the risk in whichphotoresist in any contact hole disappears while etching. In this way,it is possible to prevent any contact hole from penetrating through tolower conducting layers.

In addition, by forming a contact hole pattern on a silicon nitride filmby using lithography, it is also possible to use what is called a hardmask. In this case, a positive photoresist, which has a high resolutionproperty, may be used.

Following this, an oxide layer is formed on a part of a conducting layerwhich is exposed on the side surface of each contact hole. For example,a thermal oxidization process is performed and an oxide layer is formedon a part of a conducting layer which is exposed on the inside of eachcontact hole. As a result, as shown in FIG. 13, for example, an oxidelayer 2302 is formed on the part of the conducting layer 111 which isexposed on the side surface of the contact hole 2201. However, becausegenerally, the process of forming an oxide film proceeds isotropically,an oxide layer is also formed at the bottom surface of the contact hole.For example, an oxide layer 2301 is also formed in the part of theconducting layer which becomes the bottom surface of the contact hole2202. Then, anisotropic etching process such as RIE is performed and theoxide layer 2301 of the conducting layer at the bottom surface part ofthe contact hole is removed. As a result, the structure shown in FIG. 14is obtained.

In addition, the volume of an oxide layer often becomes larger than theoriginal volume of a conducting layer which is oxidized by thermalprocessing. Then, the shape of a contact hole becomes a shape heaving upin which the surface of oxide layers swell to the center of a contacthole compared with the surface of insulating layers.

Then, a contact metal plug (for example, the later labeled 2401 in FIG.15), which is made of, for example, tungsten or silicon which has beendoped with phosphorus, is deposited inside the contact holes 2001, 2101,2201 and 2202. After the deposition of contact metal plug, the uppersurface of the stacked multilayer structure is planarized by CMP(Chemical Mechanical Polishing), for example (FIG. 16).

Because each oxide layer which is formed on each conducting layer at theside of a contact hole has insulating properties, each contact isconnected electronically only to the conducting layer which is at thebottom of that contact. In addition, because the oxide layer 2302 isformed by thermal oxidization, it has a good adhesion property with aconductor. Therefore there is little possibility in which the oxidelayer is stripped off from the conducting layer at the time ofdepositing a contact metal plug.

Here, because the topmost layer of the stacked multilayer structure iscomposed of the single layer as the insulating layer 112 or theinsulating layer 114 formed as a protection layer, there is littlepossibility for dishing phenomena to occur during the CMP process. As aresult, crumbling, for example, of the pattern of wires on the topmostlayer hardly occur.

Furthermore, in FIG. 10 to FIG. 16, the side surface of the contactholes which are formed by etching are shown to be perpendicular to thebottom substrate. However, actually, the contact holes may also have abarrel shape in which the hole expands on half-way, or a taper shape inwhich the diameter of the hole becomes larger towards the top of thehole, or an opposite taper shape in which the diameter of the holebecomes larger towards the bottom of the hole. These shapes are notexcluded from the embodiments of the present invention.

Fourth Embodiment

In the third embodiment describe above, by forming an oxide layer on thesurface of a part of each conducting layer which a contact holepenetrates, it is possible to realize an insulation of one or moreconducting layers other than the conducting layer at the bottom surfaceof a contact hole. Embodiments of the present invention are not limitedto the realization of insulation of this type. A variety of methods arepossible.

For example, after obtaining the structure shown in FIG. 12, instead ofperforming an oxidization process, an insulating film may be formed onthe inside surface of each contact hole. It is possible to use CVD(Chemical Vapor Deposition) or ALD (Atomic Layer Deposition), forexample, to form the insulating film of SiO₂ etc. As a result, as shownin FIG. 17, a structure is obtained in which the insulating film 2601 isformed on the inside surface of a contact hole.

Following this, the bottom surface of a contact hole is anisotropicallyetched by, for example, RIE process, the conducting layer at the bottomsurface is exposed, a contact metal plug is deposited and the contact2701 is obtained as shown in FIG. 18. In this way, it is possible tomake each contact connected electronically to the bottom conductinglayer and insulated from other conducting layers.

Fifth Embodiment

In the third and fourth embodiments, an explanation is mainly given sothat contact holes are formed one by one. However, the scope of thepresent invention is not limited to this type of formation. For example,a plurality of contact holes which reach the same conducting layer maybe simultaneously formed. I.e., two or more contact holes have the samedepth at this stage. Then, in each of one part of these contact holes,which may be roughly half of them, another contact hole is formed toreach a lower conducting layer. Aside this example, there are, forexample, contact hole H₁ and contact hole H₂, and H₁ and H₂ reachdifferent conducting layers, and if there is a need to form contactholes which is in contact with conducting layers which is N layers lowerthan the layers H₁ and H₂ reach, further contact holes may be formedsimultaneously penetrating the bottom surfaces of H₁ and H₂.

For example, after the stacked multilayer structure shown in FIG. 9 isobtained, by the same process as in the third embodiment, a mask isformed using a photo resist 113 as shown in FIG. 19, and the two contactholes 2801 and 2802 which reaches the conducting layer 107 are formed bythe same etching process. Following this, the photoresist 113 isremoved.

After this, a photoresist is deposited as shown in FIG. 20 so that thecontact holes 2801 and 2802 are not etched further. Following this, apattern is formed using a photoresist 2901 for forming two furthercontact holes by lithography.

Then, the contact holes 3001 and 3002 which reach the conducting layer111 are formed by the same etching process as shown in FIG. 21.

Following this, the photoresist 2901 is removed and another photoresist3103 is deposited. Then, the contact hole patterns 3104 and 3105 areformed using the photoresist as shown in FIG. 22, so that two contactholes each of which will reach yet a lower conducting layer are formedfrom the bottom surfaces of the contact holes 2801 and 3001respectively. That is, the openings 3104 and 3105 which reach the bottomparts of the contact holes 2801 and 3001 are formed in the layer of thephotoresist. The inner diameter and bottom surface respectively of theopenings 3104 and 3105 may be formed to match the inner diameter andbottom surface respectively of the contact holes 2801 and 3001. Theymay, however, be different. In FIG. 22, the case where the innerdiameter respectively of the openings 3104 and 3105 is smaller than theinner diameter respectively of the openings of 2801 and 3001respectively is shown.

Then, an etching process in which from the bottom surface of each ofcontact holes 2801 and 3001, another contact hole which penetrate theinsulating layer at the bottom surface of each of the contact holes 2801and 3001 and reach the lower conducting layer. After this process, byremoving the photoresist 3103, the contact holes 3001 and 3002 and thecontact holes 2801 and 3201 which are sectioned into the upper part andlower part by the conducting layers 111 and 107 are obtained as shown inFIG. 23.

Following this, as in the first embodiment of the present invention, anoxide film is formed on the conducting layer exposed on the side surfaceof each contact hole. The thickness of the oxide film which is formed onthe side surface is set so that it is thicker than the differencebetween the inner diameter of the contact holes 2801 and 3001 and theinner diameter of the contact holes 3201 and 3202 respectively. Etchingprocess such as RIE is performed on the bottom surface of the contacthole and the oxide film is removed from the bottom surface. As a result,the structure as shown in FIG. 24 is obtained. The parts which arehatched such as the part with the symbol 3302 shows an oxide film.

As is shown in FIG. 24, when the oxide film which is formed on thebottom surface of the contact holes 2802, 3002, 3202 and 3304 isremoved, the upper parts of the oxide film 3302 and 3303 which aresimultaneously formed on the step part are somewhat removed. However,because the film thickness of the oxide films 3302 and 3303 is formed sothat it may be thicker than the difference between the inner diameter ofthe contact holes 2801 and 3001 and the inner diameter of the contactholes 3202 and 3304 respectively, the insulating layer 3302 and 3303still remain on the side surface which is in contact with the contactholes of the conducting layers 111 and 107 respectively. Furthermore,the thickness of the upper part of the oxide films 3302 and 3303 whichare removed is almost the same thickness as the oxide film which isformed on the bottom surface of a contact hole.

Following this, as in the third embodiment, a contact metal plug isdeposited and the contacts 3305, 3306, 3307 and 3308 which conductelectrically only with the conducting layers at the bottom surface ofthese contacts, are formed by a process in which the upper part of thecontact metal plug is planarized.

That is, the contact 3308 comprises (1) an upper part contact the bottomsurface of which is in the middle of the conducting layer 107 and (2) anlower part contact the bottom surface of which in the middle of theconducting layer 105, and the inner diameter of the lower part contactis smaller than the inner diameter of the upper part contact. Further,the upper part contact is stacked on the lower part contact. There is acontact 3307 above the same substrate layer 103 which has almost thesame inner diameter as the upper part contact of the contact 3308. Thecontact 3307 reaches the conducting layer 107. In addition, byincreasing the number of stacked layers, a contact may have threeseparate parts, namely, an upper, middle, and lower contact and may beformed with many more parts. There may be many contacts above the samesubstrate layer 103 each having a different number of parts.

Also, as in FIG. 26, even in the case where the thickness of the oxidefilm 3303 which is formed on a side surface is not thicker than thedifference between the inner diameter of the contact hole 3001 and theinner diameter of the contact hole 3202, by adjusting the amount of RIEetching and the thickness of the oxide film which is formed on thecorner part 3303 of a conducting layer, it is possible to leave an oxidefilm on the side surface which reaches a contact hole of a conductinglayer.

In addition, as shown in the fourth embodiment of the present invention,an insulating layer is formed on the inner side of a contact hole, andit is possible to remove the bottom insulating film by etching using RIEfor example. In this case, the stacked multilayer structure shown inFIG. 27 is obtained as a stacked multilayer structure related to oneembodiment of the present invention.

In this case, when removing the oxide film of the bottom surface of acontact hole, in order to leave an oxide film on the side surface of aconducting layer, it is preferred that the thickness of the oxide film3401 which is formed on the side surface be formed so that it is thickerthan the difference between the inner diameter of the contact holes 28013001 and the inner diameter of the contact holes 3201 and 3202respectively.

In addition, as shown in FIG. 28, even in the case where the thicknessof the oxide film, which is formed on a side surface, is not thickerthan the difference between the inner diameter of the contact hole 3001and the inner diameter of the contact hole 3201, by adjusting the amountof RIE etching and the film thickness of the oxide layer, which isformed on the corner part of a conducting layer, it is possible to leavean oxide film on the side surface which is in contact with a contacthole of a conducting layer.

According to the present embodiment, several contact holes which reachthe same conducting layer are formed simultaneously and a furthercontact hole is formed from the bottom surface of a contact hole amongthem so that the further contact hole reaches a different conductinglayer. In this way, it is possible to obtain a stacked multilayerstructure with a fewer number of processes which comprise depositing aphoto resist, forming a pattern by photolithography and etching.

By selecting an order for forming contact holes it is generally possibleto form contact holes on a stacked multilayer structure by a number oftimes of a logarithmic order of the number of contact holes which are tobe formed (or the number of conducting layers). For example, assumingeight contact holes are to be formed, the depth of a contact hole isrepresented as a natural number which showing how many layers thecontact hole penetrates (zero represents a contact hole which is notformed yet), and the depths of eight contact holes are represented as acombination of eight natural numbers such as (a, b, c, d, e, f, g, h).First, four contact holes with a depth of five are formed and (0, 0, 0,0, 5, 5, 5, 5) is obtained. Next, four contact holes with a depth of oneare formed at a position where a contact hole is not formed and (1, 1,1, 1, 5, 5, 5, 5) is obtained. Then, two contact holes with a depth ofone and two contact holes with a depth of five are selected and twocontact holes with a depth of two are formed on each respectively and(1, 1, 3, 3, 5, 5, 7, 7) is obtained. Then, one contact hole with adepth of one, one contact hole with a depth of three, one contact holewith a depth of five and one contact hole with a depth of seven areselected and a further contact holes with a depth of one is formed and(1, 2, 3, 4, 5, 6, 7, 8) is obtained. Therefore, eight contact holes areobtained in four times.

Alternatively, formation of four contact holes has been explainedreferring to FIG. 19 to FIG. 28 in the present embodiment, however, whenexpressed using the same notation, because they become (0, 0, 3, 3), (1,1, 3, 3), (1, 2, 3, 4), four contact holes are obtained in three times.Therefore, while the number of contact holes is doubled from four toeight the number of times has only increase by one.

While, the shape of the side surface of a contact hole is shown asperpendicular to the substrate layer 103 in FIG. 23 for example,however, as stated above, the side surface may have a variety of shapessuch as a barrel shape, a taper shape or an opposite taper shape. Inaddition, in the case where a further contact hole H₄ is formed from thebottom surface of the contact hole H₃, the shape of H₃ and H₄ can bedifferent.

Sixth Embodiment

In the embodiments explained above, the inner diameter and the shape(for example, the bottom surface shape) of a contact hole has not beenparticularly referred to. If the inner diameter and the shape (forexample, bottom surface shape) of a contact hole is the same, generally,the deeper a contact hole is the greater the electrical resistancebecomes. When the electrical resistance is different between contactsthere is a possibility that reliability may decrease and therefore it ispreferred that any difference in electrical resistance between contactsbe small or zero.

Thus, in the present embodiment, the diameter of contact holes and theshape of contact holes which reach lower conducting layers are enlargedand widened respectively. In other words, the diameter of contact holesand the shape of contact holes which are in contact with higherconducting layers are reduced and narrowed respectively.

For example, assuming that in FIG. 29 the length of a plug of thecontact hole 3501 is given as L, the length of a plug of the contacthole 3502 may be given as (3/4) L, the length of a plug of the contacthole 3503 may be given as (2/4) L and the length of a plug of thecontact hole 3504 may be given as (1/4) L and using the inner diameterof the contact hole 3501 as a base, the inner diameter of the contacthole 3502 is given as [(√3)/2], the inner diameter of the contact hole3503 is given as [(√2)/2] and the inner diameter of the contact hole3504 is given as [1/2] so that electrical resistance of each of contactsto be formed in the contact holes 3501, 3502, 3503, and 3504 issubstantially the same.

The present embodiment of the present invention can also be applied tothe fifth embodiment of the present invention. That is, it is possibleto narrow not only the inner diameter of the upper part contact hole butalso the lower part contact hole which is connected to a upperconducting layer. As a result, it is possible to reduce a difference inelectrical resistance between contacts.

Seventh Embodiment

Instead of the manufacturing method of the stacked multilayer structureexplained in the above embodiments, the following manufacturing methodmay also be used.

The insulating layer 104, conducting layer 105, insulating layer 106,conducting layer 107, insulating layer 108, conducting layer 109,insulating layer 110, conducting layer 111, and the insulating layer 112are stacked alternately on the substrate layer 103. For example, anoxide silicon layer of 70 nm thickness is formed as an insulating layerby a plasma CVD method and an amorphous silicon layer of 100 nmthickness is formed as a conducting layer. This is the same as inprevious embodiments.

A photoresist layer is deposited on the topmost insulating layer 112except for, for example, the right side part and etching as far as thelowest conducting layer 105 is performed. In this way, a first step of astepped shape structure is formed.

Then, a slimming process, for example, is performed on the remainingphotoresist layer which has been formed on the topmost insulating layer112 and etching as far as the conducting layer 107 which is the secondlowest conducting layer is performed. As a result, a second step of thestepped structure is formed. Furthermore, so that the exposed part ofthe conducting layer 105 is not etched any further, the exposed partetc. is covered by a photoresist.

The above sequence is repeated and a third and a fourth steps of thestepped structure are formed. Then, an interlayer insulating layer isdeposited on the stepped structure and planarized by CMP, for example.

Following this, each contact hole which reach respective conductinglayers is formed and contacts are formed. Thus, the contacts such thatthe diameters at the upper part are larger than the diameters at thelower part are formed

Eighth Embodiment

Next, elements which are formed on a nonvolatile semiconductor devicewhich uses a stacked multilayer structure of an embodiment of thepresent invention is explained. FIG. 30 shows a memory string in anonvolatile semiconductor device shown in FIG. 7 or FIG. 8. When anonvolatile semiconductor device shown in FIG. 7 or FIG. 8 isgeneralized, it is possible to obtain a nonvolatile semiconductor devicehaving m×n (m and n are natural numbers) memory strings which are formedin a matrix shape. It is possible to specify a position of each memorystring using the number combination of a row and a column. Thus, amemory string at the m-th column and the n-th row are specified as anmn-th memory string.

The mn-th memory string 10 includes four memory transistorsMTr1mn-MTr4mn and two selection transistors SSTrmn and SDTrmn, and eachare connected in series respectively. In one of the memory strings 10, apillar shaped semiconductor 11 is formed on an N⁺ region which is formedon a P type region (P-Well region) above a semiconductor substrate. Aninsulating film 12 is formed around this and planar shaped (plateshaped) electrodes 13 a-13 f are formed around this. These electrodes 13a-13 f, the insulating film 12 and the pillar shaped semiconductor 11form the memory transistors MTr1mn-MTr4mn and the two selectiontransistors SSTrmn and SDTrmn. It is possible to use an oxide siliconfilm as the insulating film 12 of the selection transistors SSTrmn andSDTrmn. In addition, the insulating film 12 of the memory transistorsMTr1mn-MTr4mn includes an electron accumulation film and is a stackedfilm of, for example, an oxide silicon film/nitride silicon film/oxidesilicon film. The electrodes 13 b-13 e become the word lines WL1-WL4 (7)respectively, the electrode 13 f becomes the selection gate line SGDnand the electrode 13 a becomes the selection gate line SGS. In addition,a bit line BLm8 is connected to one end of a source/drain of theselection transistor SGTrmn and a source line SL (N⁺ region 15 in thisembodiment) is connected to one end of a source/drain of the selectiontransistor SSTrmn.

Further, four memory transistors MTr are connected in series to one ofthe memory strings 10 and four examples of word lines 7 are shown, butit is not limited to this. The number of memory transistors which formone memory string can be decided according to the capacity of memorydevice.

The memory string 10 includes a pillar shaped semiconductor above an N⁺region (not shown in the diagram) which is formed on a P-well region 14of a semiconductor substrate. The memory string 10 is arranged in amatrix on an inner surface which is perpendicular to the column shapedsemiconductor. Further, this pillar shaped semiconductor may also be acircular pillar or a rectangular pillar. In addition, the pillar shapedsemiconductor includes not only a symectric structure which issymmetrical around a central line but also includes a pillar shapedsemiconductor having a step by step structure such as a stacked columnshaped semiconductor having a different central line above a columnshaped semiconductor having left-right symmetry.

Ninth Embodiment

FIG. 31 shows an outline structural diagram of a different nonvolatilesemiconductor device which uses a stacked multilayer structure relatedto one embodiment of the present invention. The nonvolatilesemiconductor device 800 includes a memory element region 803, aplurality of bit lines 805, a bit line driving circuit 807, a pluralityof source lines 809, a plurality of word lines 811, and a word linedriving circuit 813. As is shown in FIG. 31, in the nonvolatilesemiconductor device 800 the memory elements 815 which form the memoryelement region 803 are formed within a stacked part in which conductinglayers and insulating layers are alternatively stacked. As is shown inFIG. 31, conducting layers which are connected to each source line 809are spread out in two dimensions.

Some parts of the conducting layers and insulating layers which projectout from the right of the memory element region 803 in the nonvolatilesemiconductor device 800 shown in FIG. 31 are drawn using dotted lines.This is to explain the structure of the contacts in the plate shapedconducting layers related to a embodiment of the present embodiment.Actually, the conducting layers and insulating layers which are abovethe lowest conducting layer extend about the same as the lowestconducting layer. That is, the conducting layers shown in grey extend aslargely as the conducting layers 105, 107, 109 and 111 in FIG. 1, FIG.3, FIG. 5 and FIG. 6. In addition, the insulating layers between eachconducting layer and the lowest and the highest insulating layer extendas largely as the insulating layers 104, 106, 108, 110, and 112.

Each of the conducting layers which are connected to each source lines809 has a planar structure which extends two-dimensionally at a certainlevel. In the nonvolatile semiconductor device 800 the direction of theelectric current which flows to the memory element 815 is fixed. Thus,the nonvolatile semiconductor device 800 is sometimes called a unipolaroperation nonvolatile semiconductor device. In addition, because thememory element 815 has a resistance change element which has a metaloxide, nonvolatile semiconductor device 800 is sometimes called anOxRRAM (Oxide Resistive RAM).

FIG. 32 (A) is a cross sectional view of one part of the memory elementregion 803 of the nonvolatile semiconductor device 800. FIG. 32 (B) is apartial enlarged view of the memory element 815 and FIG. 32 (C) is anequivalent circuit diagram of one part of the memory element 815. FIG.32 (D) is a part of an equivalent circuit diagram of the nonvolatilesemiconductor device 800. As is shown in FIG. 32 (A) the layers belowthe memory element region 803 of the nonvolatile semiconductor device800 include vertical transistors 20. Four memory elements are stackedabove the vertical transistors 20. In FIG. 32, the structure which formsthe four memory elements 15 which are stacked above the verticaltransistors 20 are called memory element string 28. The memory elementregion 3 of the non-volatile semiconductor device 800 includes, forexample, 10×20=200 memory element strings 28, as is shown in FIG. 31.

The memory element string 28 include memory elements 15 a-15 d. Thememory element 15 a includes a metal film 163 a, an oxide transitionmetal film 160 a, a metal silicide film 158 a, a shallow P typepolysilicon film 156 a, and an N type polysilicon film 144 a. The memoryelement 15 b includes a metal film 163 a, an oxide transition metal film160 a, a metal silicide film 158 b, a shallow P type polysilicon film156 b, and an N type polysilicon film 144 b. The memory element 15 cincludes a metal film 163 a, an oxide transition metal film 160 a, ametal silicide film 158 c, a shallow P type polysilicon film 156 c, andan N type polysilicon film 144 c. The memory element 15 d includes ametal film 163 a, an oxide transition metal film 160 a, a metal silicidefilm 158 d, a shallow P type polysilicon film 156 d, and an N typepolysilicon film 144 d.

Each of the memory elements 15 a-15 d which form the memory elementstring 28 has a metal film 163 a which is common to each memory elementand one end of each of the memory elements 15 a-15 d is electricallyconnected by this metal film 163 a. In addition, the n type polysiliconfilms 144 a, 144 b, 144 c, and 144 d are formed in a plate shape andform the conducting layers which are connected to each source line 809.In the memory element region 803 of the nonvolatile semiconductor device800 related to the present embodiment, the memory element string have acommonly share the N type polysilicon films 144 a, 144 b, 144 c, and 144d.

As is shown in FIG. 32 (D), the memory elements of the nonvolatilesemiconductor device 800 have a resistance change element 15 a 1 whichis formed from a metal film 163 a, an oxide transition metal film 160 a,and a metal silicide film 158 a and also includes a diode 15 a 2 whichis formed from a shallow p type polysilicon film 156 a and an N typepolysilicon film 144 a and is connected to one end of the resistancechange element 15 a 1. In other words, in the memory element 15 a of thenonvolatile semiconductor device 800, the resistance change element 15 a1 and the diode 15 a 2 are connected in series. Further, the memoryelement 15 a may be thought of as being formed from the resistancechange element 15 a 1 and the diode 15 a 2 being connected to one end ofthe memory element 15 a which forms the resistance change element 15 a1. The other memory elements 15 b-15 d include the same structure as thememory element 15 a. Further, the memory element 15 a of the nonvolatilesemiconductor device 800 related to the present embodiment includes thediode 15 a 2 which is in a forward direction facing a source line fromthe resistance change element 15 a 1 and the shallow p type polysiliconfilm 156 a and the N type polysilicon film 144 a may be formed so thatthe diode 15 a 2 faces the opposite direction.

In the nonvolatile semiconductor memory device 800, the source line 809is further connected to a source line selection transistor 26. Thissource line selection transistor 26 constitutes a driving circuit. Asstated above, the conducting layers which are connected to the sourceline 809 are formed from a memory element of one memory element stringand the same number of plate shaped conducting layers. In addition, theother end of the memory element 815 is connected to a bit line 805 (BL)via a vertical transistor 20. A bit line selection transistor 24 isconnected to one end the bit line 805 (BL). A signal is applied to thebit line 805 (BL) by this bit line selection transistor 24. A word line811 (WL) is connected to a vertical transistor 20. A signal is appliedto the word line 811 (WL) by the word line selection transistor 22.

Tenth Embodiment

Another embodiment of a nonvolatile semiconductor memory device isdisclosed. This nonvolatile semiconductor memory device also uses astacked multilayer structure related to one embodiment of the presentinvention which is formed by arranging three dimensionally phase changetype memory elements which are capable of storing data based on aphenomenon in which a different electrical resistance occurs dependingon whether a film such as Chalcogenide (GeSbTe), which is used in aDigital Versaile Disk, for example, is crystal or amorphous. FIG. 33shows a cross sectional structure of memory strings which are formed bya phase change type memory element. In FIG. 33, four phase change typememory cells TR1, TR2, TR3, and TR4 are formed on the upper part of avertical transistor TR5. These phase change type memory cells include acooling plate part at the center and a phase change type film via asurrounding film. The phase change type film is a film which is formed,for example, from the above stated GeSbTe. And, a channel is formed ineach memory cell and a gate electrode film is formed via a gateinsulating film in each memory cell. The gate electrode films areconnected to the conducting layers. These conducting layers extend intwo dimensionally (not shown in the diagram) and are stacked on eachother. And, as is shown in FIG. 1, FIG. 3, FIG. 4, FIG. 5 and FIG. 6, astacked multilayer structure of conducting layers is formed via theinsulating layers and each conducting layer is connected to a drivingcircuit via the contacts which are formed there.

FIG. 34 is a diagram which shows the relationship between a crosssection of each phase change type memory cell and an equivalent circuitdiagram of the phase change type memory cell. The phase change type filmpart operates as changeable resistance depending on a phase change and achannel, a gate insulating film, and a gate electrode film operate as atransistor.

Eleventh Embodiment

Until now, several structures of nonvolatile semiconductor memorydevices having a structure in which memory transistors having a floatinggate are arranged three dimensionally, are disclosed in FIG. 7 and FIG.8, for example, and a structure of a nonvolatile semiconductor memorydevice having a structure in which resistance change elements havingmetal oxide film are arranged three dimensionally, is disclosed in FIG.31 and a structure of a nonvolatile semiconductor memory device having astructure in which phase change memory cells are arranged threedimensionally is disclosed in FIG. 33. The semiconductor device whichuses a stacked multilayer structure of one embodiment of the presentinvention is not limited to these memory elements. For example, there isalso a nonvolatile semiconductor memory device which has a structure inwhich memory elements using a ferroelectric thin film material arearranged three dimensionally. In addition, a device can also beconsidered in which a movable structure is arranged three dimensionally.Such a movable structure may be formed using a process other thanprocesses which are used in the manufacture of semiconductor integratedcircuits. Examples of such devices comprise machine element parts,sensors, or actuators, by processing sacrifice film etching, which iscommonly used in technology area which is applied to MEMS (Micro ElectroMechanical Systems) as a device which is not a device for memory. In thepresent invention, it is assumed that these movable structures are alsoincluded in a semiconductor element. The stacked multilayer structurerelated to one embodiment of the present invention, during the formationof these devices, contact holes are formed on a stacked multilayerstructure of conducting layers and insulating layers which are connectedto semiconductor elements which are arranged on the same level layer,and after performing an insulation process such as oxidization, acontact is formed and it becomes possible to connect conducting layersto a driving circuit, for example.

To sum up, a first stacked multilayer structure having a stacked layerpart in which conducting layers and insulating layers are alternatelystacked, a plurality of contact holes which are each in contact with aconducting layer and formed from the topmost insulating layer, andcontacts which are formed in each of this plurality of contact holes isprovided.

A second stacked multilayer structure in which a part of a conductinglayer which becomes the side surface of a contact hole is oxidized inthe first stacked multilayer structure is provided.

A third stacked multilayer structure having an element region whichincludes semiconductor elements which are formed within the stackedlayer part after the stacked layer part is formed in the first stackedmultilayer structure is provided.

A fourth stacked multilayer structure having an insulating film on theside surface of the contact in the third stacked multilayer structure isprovided.

A semiconductor device which has one of a first, a second, or a thirdstacked multilayer structure is provided.

In addition, a first manufacturing method of a stacked multilayerstructure in which conducting layers and insulating layers arealternately stacked, a plurality of contact holes each of which isreaches each conducting layer are formed from the topmost insulatinglayer, a part of a conducting layer which becomes the side surface of acontact hole is oxidized, and contacts which are formed in each of thisplurality of contacts is provided.

In this first manufacturing method, after forming a predetermined numberof contact holes which reach one conducting layer, a part of thispredetermined number of contact holes are be formed which reach aconducting layer which is one layer below this conducting layer.

In addition, it is also possible to provide a second manufacturingmethod of a stacked multilayer structure in which conducting layers andinsulating layers are alternately stacked, a plurality of semiconductorelements in which an electrode is connected to each conducting layer,are formed, a plurality of contact holes which reach a conducting layerare formed from the topmost insulating layer, a part of a conductinglayer which becomes a side surface of a contact hole is oxidized, andcontacts are formed in each of this plurality of contact holes.

In addition, it is also possible to provide a third manufacturing methodof a semiconductor device in which conducting layers and insulatinglayers are alternately stacked, a plurality of semiconductor elements inwhich an electrode is connected to each conducting layer, are formed, aplurality of contact holes which are each in contact with a conductinglayer are formed from the topmost insulating layer, an insulating filmis formed on a side surface of a contact hole and contacts are formed ineach of this plurality of contacts.

In this second manufacturing method, after forming a predeterminednumber of contact holes which reach one conducting layer, a part of thispredetermined number of contact holes are formed which reach aconducting layer which is one layer below this conducting layer.

1. A stacked multilayer structure comprising: a stacked layer partincluding a plurality of conducting layers and a plurality of insulatinglayers, said plurality of insulating layers being stacked alternatelywith each layer of said plurality of conducting layers, one of saidplurality of insulating layers being a topmost layer among saidplurality of conducting layers and said plurality of insulating layers;and a plurality of contacts, each contact of said plurality of contactsbeing formed from said topmost layer and each contact of said pluralityof contacts being in contact with a respective conducting layer of saidplurality of conducting layers, a side surface of each of said pluralityof contacts being insulated from said plurality of conducting layers viaan insulating film.
 2. The stacked multilayer structure according toclaim 1, wherein said insulating film is formed from said plurality ofconducting layers, said plurality of conducting layers being oxidized.3. The stacked multilayer structure according to claim 1, wherein eachcontact of said plurality of contacts being in contact with theconductive layer at the bottom of said contact.
 4. The stackedmultilayer structure according to claim 1, wherein said insulating filmexpands towards the interior of said contact.
 5. The stacked multilayerstructure according to claim 1, wherein the larger the distance betweensaid conducting layer at the bottom of said contact and said topmostinsulating layer, the larger becomes a bottom area of said contact. 6.The stacked multilayer structure according to claim 5, wherein thebottom area of said contact is substantially proportional to a distancebetween said topmost insulating layer and said conducting layer at thebottom of said contact.
 7. The stacked multilayer structure according toclaim 1, wherein the bottom shape of said contact is substantiallycircular, a diameter of said cross section of said contact beingsubstantially proportional to the square root of a distance between saidtopmost insulating layer and said conducting layer at the bottom of saidcontact.
 8. The stacked multilayer structure according to claim 1,wherein the corss section shape of said contact is in a barrel shape, ataper shape, or an opposite taper shape.
 9. The stacked multilayerstructure according to claim 1, wherein at least one of said pluralityof contacts includes an upper and a lower part, said upper and lowerparts being separated by one of said plurality of conducting layers orone of said plurality of insulating layers, and the diameter of saidupper part is larger than the diameter of said lower part.
 10. Thestacked multilayer structure according to claim 1, wherein the centersof said plurality of contacts are arranged substantially in a straightline.
 11. The stacked multilayer structure according to claim 1, whereinthe centers of said plurality of contacts form a triangle wave, theamplitude of said triangle wave becoming larger or smaller.
 12. Anonvolatile semiconductor device comprising: a stacked layer partincluding a plurality of conducting layers, a plurality of insulatinglayers and a plurality of semiconductor pillars, said plurality ofinsulating layers being stacked alternately with each layer of saidplurality of conducting layers, one of said plurality of insulatinglayers being a topmost layer among said plurality of conducting layersand said plurality of insulating layers, and each of said plurality ofsemiconductor pillars having a nonvolatile memory cell around thesection of penetration into each of said plurality of conducting layers;a plurality of contacts, each contact of said plurality of contactsbeing formed from said topmost layer and each contact of said pluralityof contacts being in contact with a respective conducting layer of saidplurality of conducting layers, a side surface of each of said pluralityof contacts being insulated from said plurality of conducting layers viaan insulating film; and a driving circuit being connected to each ofsaid plurality of conducting layers respectively via said plurality ofcontacts.
 13. The nonvolatile semiconductor device according to claim12, wherein said plurality of nonvolatile memory cells includes aplurality of nonvolatile memory cell transistors and each of saidplurality of conducting layers is a common word line layer connected toa gate electrode of one of said plurality of nonvolatile memory celltransistors.
 14. The nonvolatile semiconductor device according to claim12, wherein said plurality of nonvolatile memory cells includes aplurality of resistance change elements and each of said plurality ofconducting layers is a common source line layers connected to a gateelectrode of one of said plurality of resistance change elements.
 15. Amanufacturing method of a stacked multilayer structure comprising:stacking a conducting layer and a plurality of insulating layeralternately, one of said insulating layer being a topmost layer among aplurality of insulating layers and a plurality of conducting layers;forming a plurality of contact holes, each bottom surface of saidplurality of contact holes being in contact with said conducting layersrespectively from said topmost layer; forming an insulating film on aside surface of said plurality of contact holes; and forming contacts bydepositing conducting material inside said plurality of contact holes.16. The manufacturing method of a stacked multilayer structure accordingto claim 15, wherein said insulating film is formed in an oxidizationprocess of a part of each of said conducting layer, said part of each ofconducting layers being exposed in one of said plurality of contactholes.
 17. The manufacturing method of a stacked multilayer structureaccording to claim 16, wherein each bottom of said plurality of contactholes is etched after the formation of said insulating film.
 18. Themanufacturing method of a stacked multilayer structure according to oneof claim 15, wherein after said insulating film is formed, and thebottom surface of said plurality of contact hole is etched.
 19. Themanufacturing method of a stacked multilayer structure according toclaim 15, wherein at the time of forming said plurality of contactholes, a first contact hole group including two or more contact holeswhich are in contact with a first conducting layers are formed and asecond contact hole which is in contact with a second conducting layerwhich is below said first conducting layer in a contact hole.
 20. Themanufacturing method of a stacked multilayer structure according toclaim 19, wherein said second contact hole is formed in said firstcontact hole group of substantially a half of said group of two or morecontact holes.